Console-to-JAMMA DIY Success!

Don't attempt this unless you have at a bare minimum a soldering iron and the requisite skills, a crimping tool, and lots of patience as you'll need to source parts and put in the sweat. I would recommend that you just buy those available productions and support those developers outright. I recommend the Jammacon as the dev, @TheLastBandit, has been a really cool guy in my discussions with him. Personally, I am waiting for viletim to produce SCART2JAMMA 3.0 and will definitely pick that up as it has component video (YPbPr) to JAMMA video transcoding. I have multiple cabs and it would be nice to be able to hookup more than one console to different cabs at the same time. Also, I am impatient and don't know when viletim will release his new SCART2JAMMA, plus arcade projects are fun as long as you find the time to work on them =)

What I'll discuss here is interfacing the following consoles to a JAMMA arcade: PS1, PS2, Saturn, & Dreamcast. Eventually, I would like to interface the Wii to JAMMA arcade just for Tatsunoko vs. Capcom. If you have access to a PAL Wii, you should be able to follow this to accomplish the task (I think, as I am not sure how PAL resolution will look on a standard res monitor). But us poor American Souls have Wii's that only support component video (hence I am awaiting viletim's next SCART2JAMMA). My reasoning for only targeting those consoles is I see no reason to play an HD-capable console on a 15khz monitor's much lower resolution. Also, the consoles that came before the PS1/Saturn generation, I feel had compromised arcade ports. Of course, some ports of arcade games were reimagined on the home console and far exceed their arcade versions (Mike Tyson's Punchout, Rygar). It wasn't until the 128-bit generation that home console performance began to match or exceed the performance of arcade games; Tekken Tag Tournament and Soul Calibur being good examples of this. I wish to play games series that started life in arcades and finished on consoles (R-Type, Gradius, etc.). Or games that were inspired by arcade gameplay but were only found on consoles (Einhander), and finally games that are too expensive or hard to source in this hobby and so I'll settle for a good home console port over MAME (think Cave titles). Some games just need to be experienced on a cab with the faint glow of marquee light radiating on your face. The rest of the games in any console's great library I feel are best experienced with a gamepad from the comfort of your couch. You may feel differently and can certainly apply this discussion to interface other consoles to play whatever you like on your cab(s).

The consoles I am targeting natively support RGB output through their AV connections. Best to harvest the RGB signal from the consoles with proper SCART cables. The SCART cable also harvests the line level stereo audio from your console which we will discuss later. Along with RGB, you will need to harvest:

5 volt DC on pin 8

Ground (Gnd) pin 21

Composite video (CVBS) on pin 19 for which we will strip out composite sync (CSync)

Video Ground (VGnd) on pin 17

RGB are on pins 15, 11, and 7 respectively

Here is the best pinout diagram of the signals we will need to harvest from SCART for this effort that I could find: msx.org/wiki/SCART_connector

BUY GOOD QUALITY CABLES from reputable producers. I can't stress that enough:

Retro-access.com if you are in the US has the best reputation for SCART cables. But you have a very small window of opportunity to purchase from her as she opens up business at 4:30am PST and closes up shop quickly

thefoo83@gmail.com right now is probably the only producer of quality aftermarket Dreamcast SCART cables. Here is his eBay page. Email him with what you want instead of buying from eBay and you'll both save some money (he doesn't pay eBay fees and passes that saving to you). Really responsive and cool guy, btw. I got cables from him in about a week.

If you are in the Europe, you should have no problem sourcing quality RGB cables for your consoles

For this discussion, get the CSync version of the SCART cable for your console instead of the Luma Sync (Sync-on-Luma) version of the cables. This saves you from building the sync stripper circuit. Some of you may already have SCART cables for connection to one of those commercial RGB monitors, or plan to. In that case, purchase the cable that suits your situation: w/CSync built-in or Sync on Luma Sync. Also, if given the option, get the cables that do not have the 220uf capacitors or desolder them from your cables. Here is an explanation of why. Now off to building an adapter that the SCART cables shall plug into eventually outputting video to JAMMA 15khz standard.

We will use the THS7316 video amp for transcoding the RGB signal. The THS7374 amp is also an option as it is the newer 4 channel version of the THS7316 amp that allows the low pass filter (LPF) to be disabled and the 4th channel to amp CSync. But amping CSync isn't necessary for this purpose. Also, disabling the LPF doesn't improve things for analog video applications according to Bob's (retroRGB) site. It is also much smaller and harder to solder than the THS7316. Speaking of which, we are also going to borrow from Bob's site most of what is needed to build this circuit with these key differences:

Skip the installation of the 0.1uf capacitor entirely. Seems for this purpose, that cap introduces video noise. Whereas with Bob's application, console modding for play on an PVM/BVM or through an OSSC or Scanmeister, it does not

The resistors need to be installed on the RGB input lines, rather than the RGB out lines

Additionally, the resistors need to be terminated to ground before the RGB line are soldered into the inputs of the circuit. Big thanks to buttersoft over at Shmups for his help in getting me over this hump.

75 ohm termination is required to drive output DC-coupling on the THS73716/74. You can read about this on the datasheet on page 17.

Here is a pic and instructions on how I did this (I am sure someone else can do this more elegantly):

(ignore that I have the 0.1uf cap installed over 5v and Ground in this photo. Ignore that I have the resistors on the outpuut. You should not install that cap for this effort as it adds noise and the resistors should only be installed on the input).

I stripped back about 1/8" of insulation on the RGB input wires exposing some copper. I coiled one end of the resistor around a very thin precision screwdriver. Then positioned the resulting coil over the exposed part of the input wire. Placed one drop of flux on the coil and applied solder to complete the joint. The other end of the resistors are ready to be tied together and soldered to ground. Now that the video amp circuit is done, off to build the sync stripper.

If your SCART cables have CSync built-in, you don't have to build a sync stripper cicuit. You can just harvest the CSync signal from your SCART cable. If not, simply follow the guide posted over at Bob's site to build the circuit. Now you are ready to wire your amped RGB, VGnd, and CSync lines to your SCART adapter. Depending on how creative you want to be and how elegant looking your final product is to be, you have options for your SCART adapter:

I have a Sync Strike that I plug my SCART cables into. This was sort of an impulse buy from me when I was researching this stuff. I don't even have a BVM monitor or ever intend to get one. But the purchase has turned out well for this purpose as It does a fine job of harvesting the signals I need. Sort of expensive but I'd recommend it since it saves a lot of time sourcing parts and greatly reduces the effort:

Very poor documentation on this little device. As a matter of fact, this is probably the best photo of the device you can find on the Net.

With the Sync Strike, I don't have to build a sync stripper circuit to harvest CSync. I also don't have to buy cables w/CSync. RGB, CSync, and VGnd are readily available from the screw terminals. I just need to tap into the 5vdc and Gnd on the SCART connection to power the THS7316 RGB amp.

Here is a shot of where I tapped into 5vdc and Gnd off the Sync Strike from the solder side. Now I run all the signals I need, RGB, 5vdc, and Gnd into the RGB amp. Coming out of the amp is the transcoded/amped RGB suitable for JAMMA connection. I couple that transcoded/amped RGB signal with the CSync and VGnd signals that are coming off the Sync Strike screw terminals and plug that into a JAMMA fingerboard with a 5-position JST NH connector (you can solder this in as an option. I have these connectors handy). As far as JAMMA fingerboards go, the best one on the market is the PB.Jamma (PB stands for Project Board) since it has properties that will lend very well to us later with control interfacing. Big thanks to @Lemony Vengeance for his efforts in designing this board.

You can skip the Sync Strike if you wish to simply build an adapter to harvest the signals you need from SCART. If so, here are some options:

You can use female SCART plugs, but you have to buy them in bulk if you are in the US. Unless you can find them somewhere sold individually.

Can't buy PCB's for the final sequels for these arcade originated game series anywhere!

The image is on the left shows the image with the 0.1uf cap installed on the amp. The one on the right shows the image without the 0.1uf cap. You'll see the right image has much less noise. Bottom-line, don't install that cap for this purpose.

The image on the left shows the 220uf caps installed inside the SCART cable hood on the RGB signal lines. The image on the right has those caps removed. Bottom-line, you don't need 220uf caps for this purpose. Buy your SCART cables without those caps or desolder them from your cables.

Two last thing that I'll say:

Some monitors can accept the RGB signal from a console. So far, my Wells Gardner K7000 monitor and my Neotec monitors can. viletim calls these domestic monitors (US made monitors). These monitors use the same parts from TV's so they can be used to some extent without building the amp. If you only have one cab and it has such a monitor, you might get away without building the amp. You'll definitely need to recalibrate the image. But if you have a candy cab with Japanese monitors, you need the amp.

This amp should work for amping, clamping, DC-restoring and DC-coupling your CRT_Emu MAME rigs. I haven't tried it yet. Saves you from buying Ultimarc's Video amp or the J-Pac. Now you can use real joystick PCB's rather than using the J-Pac's keyboard encoder.

The video interfacing portion is now complete. Off to audio interfacing!!

JAMMA audio is mono and amped from the PCB. Volume is controlled either through a physical pot on the board or in the test menu of the PCB. The other dilemma is that console audio is line level stereo. We need to figure out a way to mux the stereo signal to mono, which is simple enough. But we also have to have a way to amp the signal. On the other hand, why down mux the superior stereo signal to mono? Why not just leave it as stereo? But if we leave it as stereo, we have to amp the signal as well. Here in is the crux of the problem. Here is how I think we can have both or either or.

If you have a dedicated stereo JAMMA cab:

You're in luck! This requires the least amount of work, parts sourcing, and thought to solve for. Simply harvest Audio-Left, Audio-Right, & Audio-Ground from your SCART adapter. Here again is the SCART pinout. Terminate those signals lines to either:

Female RCA terminal connector like this or like this, depending on how clean you envision your finished product to be

The only other consideration here is if the stereo amp in your JAMMA cab has a volume control. Some such as the Capcom Big Blue's Q-Sound amp or Sega's NAOMI amp do not have volume control. Volume is rather controlled on the PCB or is wired to to yet another volume control knob installed somewhere in the cab (usually inside the coin mech just above the coin drop in US cabs). If your amp does not have volume control, you will need to add some inline volume control. Here is an example of one for 3.5mm stereo jack cables. Here is an example of one for RCA stereo volume control. Which one you will use will depend on your cab's audio connection and how far you are willing to go to source parts.

If you have a single speaker JAMMA cab:

This is your plain ol' vanilla JAMMA cab from the early 90's and earlier. Think of those Dynamo's and Z-backs that were at every 7-11 back in the days. What you'll need here is to add in an amp to juice the audio signal. Then downmux the stereo audio to mono by building this resistor network:

Here is a good video that explains the process; this is for another application but the principles are the same. Finally, making the connection to your JAMMA fingerboard through your JAMMA edge connector to your speaker. To power the amp, you'll need to harvest the 5v signal from your SCART adapter. Optionally, you can use a more powerful amp, but you will need to figure out how to power that amp externally. For my purposes, I will be throwing everything into a project box. Therefore, I will need an amp small enough to fit inside the project box. I also don't want to run external power into the project box (unless I have to). I want to power the video amp, the sync stripper, and the audio amp from the SCART adapter's 5vdc signal. Lots of options for a 5v stereo amp. The one I chose is based around the PAM8406 circuit.

If you have a dual speaker JAMMA cab:

These cabs are just like the previous cab mentioned above but were setup with two speakers instead of a single one. Or once they were out in operation, they may have been modified and a 2nd speaker was added to the cab. In any case, the sound coming from each speaker is mono. The audio signal wire is simply daisy chained to both speakers. You have 3 options here:

Keep it as a JAMMA audio dual speaker cab

If so, just wire into the JAMMA harness with the instructions explained in the "If you have a single speaker JAMMA cab" section above

Convert it to a stereo JAMMA cab

If so, you'll need to install an external audio amp and figure out how to power it

In this day and age, some of the amps the MAME guys use do really well in these scenarios and you have lots of choice: the aforementioned PAM8406, if you need more power you can use a TDA-based stereo amp, or a Lepai amp gives you a bit more flexibility.

All are good choices for this purpose. Keep in mind, you will be standing a foot away from the speakers. You don't need a huge hi-fidelity solution here.

Finally, you can rewire your cab to allow the flexibility to switch back and forth from JAMMA mono to stereo with a bit of manual switching

Run speaker cables to both of your speakers, then terminate them to 0.62 6-postion molex connector, or something similar. This is where the manual switching will be applied, so no black electrical tape rigging here. I have never seen a 0.62 4-position molex connector. But that is okay if we leave 2 of the 6 positions unused.

From your JAMMA harness, terminate the +/- speaker signal so that there is a tag end hanging off each pin long enough to crimp in another pin. The extra pin off the tag end is a jumper/daisy chain which allows the same mono audio signal to be sent to both speakers. Just make sure you have the polarities right: negative to negative, positive to positive. This is how I have seen it done on numerous US cabs when there is a need to switch back and forth between a mono JAMMA setup to a stereo setup. There is probably a way to do this without manual switching. But then again, what's a little manual switching compared to the cost of more money?

Now make another plug that will fit into the speaker terminal plug. This time however, run one wire for each speaker since this will be our stereo setup (no jumpering/daisy chaining). Leave a length long enough to reach where you will place your JAMMA adapter.

[RESERVED for Pics]

I am going to throw this adapter into a project box, whereby the amp will be fitted in. I want to be able to take the adapter I am building to a buddy's house and plug it into another JAMMA cab. At home, I want stereo sound. I'll build this into a project box where I can have both one at a time.

I'll need a triple pull double throw (3PDT) switch to achieve this

I'll also need stereo speakter terminals like this or like this. This is all preference as to how you want this here.

The wiring from the SCART adapter will go like this: SCART stereo audio->5v stereo audio Amp->3PDT Switch. Then from the 3PDT switch,

In position 1:

Wire into the resistor network described above downmixing stereo to mono. Eventually this will be connected into the JAMMA fingerboard

In Postion 2:

Wire into the stereo speaker terminals. The signal will be amped stereo. So from the stereo speaker terminals on the project box, this can be wired right into the speaker plug described earlier.

If want line level stereo output and amped mono for JAMMA, then the wiring needs to be changed to SCART stereo audio->3PDT switch, then from 3PDT:

I've built a JAMMA converter for the Megadrive. It plugs into the DIN video and audio connector at the back, video signals are then amplified to JAMMA standard and audio is amplified with a 4W audio amp (more than enough for home use). Two connectors plugs into the cartridge ports with two LS157 multiplexer. 3 buttons only but first JAMMA was OG designed to be 3 buttons only and second 95% (if not more) or MD games use only 3 buttons. Don't tell me about SF2, I built this adapter to play MD games, if I want to play SF2 I hook up the CPS1
I made it because I was horrified to see what the available solutions were, like butchering a MD when everything can be done without any hardware modification to the console.

Selling files for conversions/desuicide on Sega System C2/Sega System 24/Sega System 32, Capcom CPS1, Irem M92/M107 and more (just ask)
Money is reinvested in boards, parts and tools in order to release more stuff.
Contact me through my blog: arcadefixer.blogspot.co.nz/

Selling files for conversions/desuicide on Sega System C2/Sega System 24/Sega System 32, Capcom CPS1, Irem M92/M107 and more (just ask)
Money is reinvested in boards, parts and tools in order to release more stuff.
Contact me through my blog: arcadefixer.blogspot.co.nz/

Ahh, k. I have a few THS7374's. Waiting on the SOIC14 PCB's to arrive from China to test them out. By any chance, did you disable the LPF and does it make any difference for this application? Right now I am getting some rather stunningly sharp RGB. Wondering if it is worth the effort:

(Side rant: Best version of Soul Calibur ever and you can't play it on a NAOMI)

By any chance, did you disable the LPF and does it make any difference for this application?

Nope and never tried to disable the filter. Just works fine.

Selling files for conversions/desuicide on Sega System C2/Sega System 24/Sega System 32, Capcom CPS1, Irem M92/M107 and more (just ask)
Money is reinvested in boards, parts and tools in order to release more stuff.
Contact me through my blog: arcadefixer.blogspot.co.nz/

I'll add some diodes to the 5v lines (yellow) to make sure the voltages flow the right way as I tap into pin 8 on the SCART socket. Other than that, this is pretty straight forward from here. This one will be used for my cab with a external stereo amp (Big Blue).

Finally, my SSOP PCB's arrived from China! Now I can check out the THS7374 RGB amp to see if disabling the Low Pass Filter (LPF) makes any difference (which is unlikely). Also, these are 28 position chips with SOP and SSOP solder spacing on the flip side. Here is a shot of what I mean:

On the left, is the smaller spaced SSOP package. On the right is the wider spaced SOP package. What this allows me to do is fit the THS7374 RGB amp to the SSOP side and the LM1881 sync stripper on SOP side and use the same PCB. Alternately, I can fit the THS7316 and the LM1881 chips on the SOP side of the PCB if that is the amp I (or you) decide to go with. I even get pins to spare which I can use for distributing power or ground by jumping the breakout pins and solder bridging the unused solder pads. Woot!

I don't know about you guys, but it takes now about 1.5 months to get stuff from China since the tarifs have been announced. Used to be about 2 weeks :/. I had to wait a while for these but they are here. This is the first time I have ever soldered an SMD package this small and it wasn't so bad. I tested it with my meter and there are no solder bridges. Big thanks to the folks over on this thread for their suggestions on eyewear. Also, watched all of this guy's videos on Youtube. Makes SMD soldering a whole lot easier. Check out the pimp work below!

I don't know about you guys, but it takes now about 1.5 months to get stuff from China since the tarifs have been announced. Used to be about 2 weeks :/. I had to wait a while for these but they are here.

I'm not in the US but I've noticed something similar since February. I'm still waiting for things to come in the mail I ordered 6 weeks or more ago. From different suppliers so don't think they all got lost.

Selling files for conversions/desuicide on Sega System C2/Sega System 24/Sega System 32, Capcom CPS1, Irem M92/M107 and more (just ask)
Money is reinvested in boards, parts and tools in order to release more stuff.
Contact me through my blog: arcadefixer.blogspot.co.nz/

Hey guys, any interest in or advice for splitting JAMMA RGB out to something like an OSSC (and doing it properly, with no dimming)? I've seen suggestions that AV3 is the best OSSC input, due to accepting TTL sync, but junkerhq also notes that the input is AC-coupled. I haven't quite got my head around how to accomplish that with a THS amp.